docs: def remove_index(self, field=None, value=None):
          """
          remove_index(field=None, value=None)
  
          Remove the specified field/value pair as an index on this
          object.
  
          :param field: The index field.
          :type field: string
          :param value: The index value.
          :type value: string or integer
          :rtype: :class:`RiakObject <riak.riak_object.RiakObject>`
          """
          if not field and not value:
              self.indexes.clear()
          elif field and not value:
              for index in [x for x in self.indexes if x[0] == field]:
                  self.indexes.remove(index)
          elif field and value:
              self.indexes.remove((field, value))
          else:
              raise RiakError("Cannot pass value without a field"
                              " name while removing index")
  
          return self._robject